Recovery of molybdenum compounds



Patented Feb. 8, 1 949 2,450,975 nucorwnnx or momnnnnemloomounns .lv iohoew .fiatoee a-N a a l s, N- X assi no t l pitefii iates adium Qo po at n, a

cor o ation QfiD'ilp 1N0 Drawing .ilinnlication-iflooember :28, 1944,

ssp fifl :No. 57 .921

I m (CL-213551) v' ili i e ion e ate rt -th pre a ati n and e ew o mo c de om o nd ir m t mate ials n eoueou so utionstq cte nioe both mo bdenum nd un s en eem oon Mo rboeomn i ung i eq oc th i e de osits -$ono n contain readily separable tungsten an d-an olytbdenum-nnne ele, but ,thereare large louaotities 1 ores in wh ohh un s e and mol bdenum m n r a e n t e i s parab e. Fo lexmgl l in some eolhee te ore mo d num lpres ntas an isomorphic f ylaqemqm o iungstenr Because of the ii w ty o s parat tun s en an :molrm eem-m n rals f om e ch ot r i thi -WM QT re by ordina y ap ehan eel meth d oi-e n nation; orelo i ub ected to c em a eat ent to oi 9 el hmo bc meno e sten therefrom. "libis itreament produces aq o s so ut on eoota ins t molyl e enem n un s en 7 com ounds as the so ti n mu t n be t ate -to r oote sepa ate y mo ybdenu nd tun en npoun efiim l so u on r sult om h trea ment o mo y denum-bearin rap w ich m e eeem oon aminated by associa e oest oveloea e i It is the principal Object of the presentinyene tion top ovide a e oe xoi ei a defie ent p o ess for e rin a o y e som one f om aqueous solution conta ning both molybdenum and tungstencom-pounds, More'specifically itlis an object of the inyentgion to produce, from a solne i ont nin t in rh eemo a d t ng en tween abo t an as preierabwbe we -o and i,

by the appropriate addition of a mineral aeid' or an alkali, and then adding to the solution a mineralacid-salt of a; diiIaient-metal selected from the group consisting of iron, cobalt, nickel and manganese. For economy and" convenience, ferrous sulfate is a preferred salt, Under these conditions there is precipitated from the solution a molybdate of the selected metal substantially free from tungsten compounds. Preferably, to promote separation of the molybdate from solu= tion by filtration the solution is heatedvsay to a te ature b t 75 a ts bo lin point during the metal salt addition.

Fo x mpl an alkaline lut o containin ium ilhee e e d odiummo bsia pi pa ed for ins a c by digestine era-e ontaining mo rh ieoonnd, ung te ne al ith, be aqueous solution of an alkali metal compound such as sodium carbonate or sodium hydroiiide having saltuoflltlie.group mentioned above. Suitablhat" least about.80 of the amount of salt required, toreact with the molybdenum in the solution is.

a strong basic. reaction at a pressure of about 30 t .299 p unds per square inch (temperature aboutlilOFC, to 198 Cv.) is treated with a mineral acidsuch as. sulfuricacid to adjust the pH of the solution toa value between about 5 and 7.5,. To this solution there is ,added, with stirring, a metal.

used. During, the addition of the metal salt the pg-Iiof the solution .willliall to about 4 to 5.5..

Molybdenumis precipitatedas a metal .moly bdatel but thetungsten remains in solution. The metal,

molybd'a'te is then separated from solution by filt a ion. A explaine above, this s p ation is promoted. if the starting solution is maintained.

at a temperature between about C. and it's boiling point during the vadjustment'offlits 121-1:

nd 321. m al 58 113 addition.

t is important that the pH of the solution be correctly adjusted-before the metal salt isaddedl} I; the initial of the solution is greater than.

'15, tnngsten will be co-precipitatedwith molybdenum upon the addition of the metal salt. If, on the other hand, the initial pH of the solution is below 5, the precipitation of molybdenum will" be suppressed. Proper adjustment of the initial pH of the solution to a value. between 5 and 7.5 makes p ssible-the recovery of about or more of molybdenum inthe solution without the recipitation of substantial quantities of tungsten when-themetal salt is added to the solution.

I f the pH. of the initial solution containing molybdenum andtungston compounds is .below .5,

a it may be raised by the add tion of an alkali metal compound having a strong basic reaction, such as a carbonate or hydroxide of an alkali metal;

The metal molybdate p od ced by th pr cess of the invention contains no serious amount of ll flllt- 9. particularly undesirable impurity. fre vou iently p esent in molybdenum compounds; ,It.

may be: calcined readily to a dust-free product,-

or. it can be smelted to produce ferrornolybdenum o co er ed, f d sir d, to alcium molybdate by d ssolvin it n an aqueous soluti n of sodium.

arbon t preferably lat a temperatur of'alo'out' on on) C. and treating-the resulting solution.

with a calcium compound such as calcium chlo ride or lime to precipitate calcium molybdate.

Ferrous molybdate produced by the method of the n ention maybe used for e amp e a e direct addition agent the manufacture of molybdenumo tain n steel.

The process of theinvention has been found to;

be economical and efllc'ient in large scale operati es-V Fo example. in one ope on 101 p unds of a roastedmol bdenum-tungsten,t s h tide containing about 5% tungsten and about 25% molybdenum we e hot digested With 4,600 pounds of sodium carbonate in aqueous solution at a steam.- pres u o 00 pounds per squareinch to produce; upon filterin 'and removal of parts by weight of sodium carbonate. tion was filtered, and to the filtrate were added insoluble residue: 50,000 pounds joi '5 solution containing about grams per liter of tungsten ture between 90 C. and its boiling'point, and

2,000 pounds of 94% sulfuric acidwereadded to adjust the pH of the solution to 7. To the solution, still maintained ata temperature not pH of the solution dropped to 4.6 during this addition. Ferrous molybdate was precipitated and was separated from the hot solution by filtration. The ferrous molybdate precipitate so produced was calcined at 750 C. and 5,060 pounds of ferrous molybdate containing 42% molybdenum and only 0.3% tungsten were produced. The sulfur content of this product was 0.03%. The recovery of molybdenum as iron molybdate was 85% of the total molybdenum fed.

The filtrate obtained after filtering and separation, of the iron molybdate precipitate was heated to a temperature between 90 C. and its boiling point and 500 pounds of hydrated lime was added. A precipitate containing a mixture of calcium molybdate and calcium tungstate was produced which contained 20% tungsten and 10% molybdenum. This product containing 93% of the total tungsten fed was treated inconventlonal manner for the recovery of tungsten.

A portion of the iron molybdate produced in the operation just described was converted to calcium molybdate. Thus, 500 parts by weight of iron molybdate were mixed with 800 parts by weight of water and treated for one hour at a temperature of about 80 C. to 90 C. with 175 The solu- 220 parts of calcium chloride, producing a precipitate of calcium molybdate. A recovery of 97.6%,of the molybdenum was obtained as calcium molybdate of high purity.

It will be apparent to those skilled in the art that the process of the invention is not limited to the treatment of any particular starting solu tion. The invention is applicable generallyto the treatment of aqueous solutions'containing both molybdenum and .tungstencompounds, no

matter from what source such solutions are obv tained.

I claim: c

1. Process which comprises adjusting the pH of an aqueous solution containing molybdenum and tungsten compounds to a value between 5 and 7.5 and adding a mineral acid salt selected from the group consisting of sulfate, chloride and nitrate of a divalentmetal selected from the group consisting of iron, nickel, cobalt and manganese to the said solution, thereby precipi tating' a molybdate of the selected metal there from without precipitating any substantial quantity of tungsten. V

.2. Process which comprisesadjusting the pH.

of an aqueous solution containing molybdenum andtungsten compounds to a value between 5 and 7.5 adding to the said solution at least about 80% of the amount of sulfateof. a divalent metal selected from the group consisting of iron, cobalt,

of an" aquedustsolution containing molybdenum and tungsten compounds to a value between 5 and 7.5 and adding to the said solution an amount of ferrous sulfate at least 80% of that theoretically suificient to react with all of the molybdenum in the said solution, thereby precipitating substantially all of the molybdenum in said solution as ferrous molybdate without precipitating any substantial quantity of tungsten.

4. Process which comprises adjusting the pH of an aqueous solution containing molybdenum and tungsten compounds to a value of between 5 and 7.5, heating said solution to a temperature between about 75 C. and its boiling point, and adding to the hot solution at least about 80% of the amount of ferrous sulfate sufficientto react with all of the molybdenum in the said solution, thereby precipitating substantially all of the molybdenum in said solution as ferrous from an aqueous solution containing both mlybdenum and tungsten compounds which comprises adjusting the pH of a solution containing molybdenum and tungsten compounds to a value be tween 5 and 7.5, adding ferrous sulfate to the said solution in a quantity at least about 80% of that theoretically sufficient to react with all of the molybdenum in said solution, thereby precipitating substantially all of said molybdenum as ferrous molybdate without precipitating and substantial quantity of tungsten, separating said ferrous molybdate from said solution, dissolving ferrous molybdate in an aqueous solution of an alkali metal compound having a strong basic reaction, and adding a calcuim compound to the solution so prepared, thereby precipitating calcium molybdate substantially free of sulfur therefrom. v I

6. A method of treating an ore material containing both molybdenum and tungsten compounds 1 to recover a molybdenum compound therefrom, which method comprises digesting such ore material at a steam pressure of about 130 to 200 pounds per square inch with an aqueous solution of an alkali metal having a tung'sten com'pounds, adjusting the pH of said solution to a value between '5 and 7.5 by adding a mineral acid thereto, and "adding ferrous 'sulfate to the saidsolution in a'namount at least of-the selected metal without precipitating any,

substantial quantity of tungsten-..

i '3. Process which'comprises 'adiustmgi th e of that theoretically sufficient to react with" all of themolybdenum in said solution, thereby precipitating molybdenum as ferrous molybdate therefrom withoutprecipitating any substantial quantity of tungsten. V

v REFERENCES CITED' The following references are of record the file of this patent:

UNITED STATES PATENTS MICHAEL QCARUSELLA.

Certificate of Correction Patent No. 2,460,975. February 8, 1949.

MICHAEL C. OAROSELLA It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 4, lines 23 and 24, claim 5, for mlybdenum read molybdenum; line 93, same claim, for the Word and read any; line 35, before ferrous insert said; line 37, same claim 5, for calcuim read calcium;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 21st day of June, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

